1. Material
- Steel (zinc plated): general use, highest strength for the price.
- Stainless steel (A2 / A4): outdoor, food, marine and corrosive environments; needs a stronger tool.
- Aluminium: light loads, aluminium parts, and where a soft insert is wanted. Match the metal to the part to avoid galvanic corrosion.
2. Head style
| Head | Use it when |
|---|---|
| Flat (large) head | The standard choice; the wide flange spreads load and supports soft or thin material. |
| Reduced (thin) head | You want the head almost flush without countersinking. |
| Countersunk head | The surface must be flush; needs a countersunk hole and enough sheet thickness. |
3. Body shape
- Round, plain: lowest cost, for light torque.
- Knurled: grips the hole wall for better resistance to spinning.
- Semi-hex and full hex: fitted in a hex hole, they give the highest torque-out resistance, for screws that are tightened hard or opened often.
4. Open or closed end
Open end nuts let a longer screw pass through. Closed end nuts seal against water, dust and fumes, and stop a screw from damaging parts behind the panel.
5. Grip range and hole size
Every rivet nut is made for a grip range: the total thickness of the parts it clamps. Below the range, the nut cannot form a proper bulge; above it, the body cannot reach behind the sheet. Drill the hole size given on the data sheet, usually only a little larger than the body. An oversize hole is the most common cause of spinning nuts.
Installation
Rivet nuts are set with a hand, battery or pneumatic riveting tool. The tool screws onto the nut thread, pulls it so the body folds into a bulge behind the sheet, then spins off. Set the stroke or pressure to the size and material, and check the first few with a test screw before running a batch.
Quick checklist
- Thread size and material
- Head style and body shape
- Open or closed end
- Sheet thickness, to match the grip range
- Hole size from the data sheet, and the tool you will use
Figures are typical values for guidance. For design, inspection and purchase, always follow the current edition of the standard on your drawing.